This invention relates to a process for preparing organo-clays and to the products of such a process.
An organo-clay is an organophilic cation-modified clay derived from a clay mineral, generally of the smectite group, for example bentonite, montmorillonite, hectorite, saponite or the like, by replacing the inorganic exchangeable cations, generally alkali or alkaline earth metal cations, which occur in the natural clay mineral by organic cations each comprising at least one hydrocarbon radical which has sufficient carbon atoms to render the surface of the cation-exchanged clay hydrophobic.
Organo-clays have been found to be very useful as thixotropic agents in organic media such as, for example, lubricating greases, oil-based drilling fluids, paints, varnishes, enamels and printing inks. However, an organo-clay is, in general, difficult to disperse in an organic medium to form the uniform gel structure which is required to thicken, or to increase the viscosity of, the organic medium. Various means have been used to improve the dispersibility of an organo-clay in an organic medium including the use of a polar organic material, such as a low molecular weight alcohol or ketone, as a dispersing aid, and the use of an excess of a specially selected organic cation in the preparation of the organo-clay.
It is an object of this invention to prepare an organo-clay which will disperse readily under low shear in an organic medium to form a homogeneous gel structure without the use of an additional polar organic material.